Automatic d.c to a.c inverter power up on load /power down no load

Automatic invertor/inverter load detection switch circuit. Inverter only powers up when a load is detected on the output, and powers down when load removed. Alows simple and safe connection to a ring main through a spare socket. ( when disconected from grid supply). Ideal for solar powered applications on lighting circuits where a.c is not required at all times..http://www.a2zconcepts.net

Category:

Science & Technology

Tags:

• invertor accessories
• invertor switch
• load switch
• current sensor
• solar power
• U.P.S
• mains backup

[tonyandlyn]

So if i watched this video right, your system works only if an type of appliance is connected, you used the light bulbs for this. The added plug into the Main/grid works as a extension cord for power, should your battery/solar panels run out of juice? Now does the device turn itself off if the plug is removed from the main/grid, or does it remain On?

[Esurname]

@tonyandlyn The first part is correct in that an appliance or load needs to be connected to power up the inverter. The inverter is then switched on using either a small relay (in parallel with the on switch) or a large relay switching the d.c to the inverter as per example. The inverter o/p is also isolated from the socket until load detected. NOTE: A reasonable load is required to switch the detection circuit say 5 to 7 watts so, within reason, the plug top pins can be touched by hand.

[Esurname]

@tonyandlyn I just made up a plug to plug lead as a simple way to connect to the wall socket , (after Isolating that ring at the CONSUMER UNIT), A completely automatic system could be designed in a PURPOSE BUILT CONSUMER UNIT.

Switching between INVERTER and GRID depending on battery charge levels and availability of grid power(power cut). Final point. The device turns itself off when the LOAD IS REMOVED ,ie there is no longer any a.c current flow between L and N .

[sirmasterpimp]

Great idea, this would work great if that could fit in little 12 volt power packs with inverters built in. I found that my little hand held inverter with a built in battery draws .3 watts of power with no load, heats up and discharges the battery. With that circuit (obviously a downsized version) I could probably squeeze some extra run time out of my device.

[Esurname]

The load sense circuit is not that big its the massive 150 amp relay on the 12v side that takes up all the space. It would be easier and more cost effective to incorporate the circuit into the inverter itself . I will build my own true sinewave inverter when I get time.

[randacnam7321]

@kode1303 No. Mains electricity is AC. The only loads that would work on DC are incandescent lamps, resistance heaters, switching power supplies and universal motors. Said load would also need a DC rated switch, as most things use AC only switches. Induction motors and transformers would be destroyed on DC. Other things just would not work.

[Esurname]

The only inverters that can be pluged directly into the socket with the grid power on are grid tied inverters but if there is a power cut they turn off. This load detector circuit will work with a mains input or an inverter input, the output is isolated from the input as well as providing the relay contact to switch on the inverter.(would inhibit switch if mains on !) A fully automatic switchover could be produced on the front end.This would be conditional.batt charged etc

[Esurname]

Without going into too much detail 240v ac is an RMS value (ROOT MEAN SQUARE) and therefore is an average voltage. The peaks would therefore have to be 1.414 * 240 = 340v dc peak positive and then alternating sinusoidaly 340v dc negative giving 680 v peak to peak.

Inverters normaly switch 12 or 24v dc through a transformer at high frequency rectify and smooth to give 340v d.c

This is then fed to an H bridge switching circuit that pwm (pulse width modulates) the 340vdc +/- TO L AND N

[kode1303]

Very useful! Just a thought from an illiterate when it comes to electricity: Would it be possible to hook up 20 12v batteries to get 240v dc and then convert to ac and then use the power as if it came from the grid?

[Kiwibear1080]

Very neat. I picked up an inverter that has a really bad no load current and have been looking to design my own switch like yours, broused in the hope of avoiding re-inventing the wheel - care to share your idea on a strictly non-commercial basis?